1. Field of the Invention
The invention relates to a bolt assembly, more particularly to a tension bolt assembly that can prevent co-rotation of a washer and a shank of a bolt member with a nut.
2. Description of the Related Art
In the construction of steel frameworks, to facilitate construction and ensure safety, tension bolt assemblies are generally used to couple articles.
Referring to FIGS. 1 and 2, a conventional tension bolt assembly 1 is adapted to bind first and second articles 2, 3, which are respectively formed with aligned through holes 21, 31 and opposing outer surfaces 22, 32. As shown, the bolt assembly 1 includes a bolt member 11, a washer 12, and a nut 13. The bolt member 11 includes a head 111 adapted to abut against the outer surface 32 of the second article 3, and a shank having a connecting section 112 connected to the head 111 and adapted to extend into the through holes 21, 31, an externally threaded section 113 connected to the connecting section 112, a breakable section 114 connected to the externally threaded section 113, and an annular groove 115 disposed between the externally threaded section 113 and the breakable section 114. The externally threaded section 113 is adapted to project from the outer surface 22 of the first article 2. The breakable section 114 is formed with a plurality of axially extending grooves.
When the bolt assembly 1 is used to bind the first and second articles 2, 3 together, the shank of the bolt member 11 is first extended through the aligned through holes 21, 31 in the first and second articles 2, 3, such that the head 111 abuts against the outer surface 32 of the second article 3. Then, the washer 12 is sleeved on the externally threaded section 113 that projects from the outer surface 22 of the first article 2, and the nut 13 engages threadedly the externally threaded section 113. Subsequently, a tool (not shown) is used to rotate the nut 13 so that the nut 13 urges the washer 12 to abut against the outer surface 22 of the first article 2. At this point, the bolt assembly 1 binds loosely the first and second articles 2, 3. Thereafter, a bolt tightening tool 8 specific for tension bolts and including inner and outer sleeves 81, 82 is used to engage the breakable section 114 and the nut 13, respectively. The outer sleeve 82 is rotated in one direction to drive the nut 13 until a deadlock occurs. Then, the inner sleeve 81 is rotated in a reverse direction until the breakable section 114 breaks away from the externally threaded section 113 at the annular groove 115 due to the shear produced by the differential movement of the inner and outer sleeves 81, 82. As such, the bolt assembly 1 is fully tightened and is in a highly tensed state.
Although the conventional tension bolt assembly 1 can firmly bind the first and second articles 2, 3 together, since the outer surfaces 22, 32 of the first and second articles 2, 3 are generally coated with a paint or other substance for purposes of corrosion prevention or enhancing appearance, the friction forces between the head 111 and the outer surface 22 of the first article 2 and that between the washer 12 and the outer surface 32 of the second article 3 are relatively small, thereby resulting in undesired co-rotation of the washer 12 with the nut 13, as well as rotation of the bolt member 11 with the nut 13, during the process of bolt tightening. As such, the locking force of the bolt assembly 1 cannot be controlled accurately.
Therefore, the main object of the present invention is to provide a bolt assembly that can prevent co-rotation of a washer and a bolt member with a nut during a bolt tightening operation.
Accordingly, a bolt assembly of this invention includes a bolt member, a washer, and a nut. The bolt member includes a head and a shank. The head has an article confronting side. The shank has a connecting section that is connected to the article confronting side of the head, an externally threaded section that extends from the connecting section, a breakable tip that extends from the externally threaded section and that is formed with a plurality of axially extending and angularly displaced teeth, and an annular groove that is formed at a juncture of the externally threaded section and the breakable tip. The washer is sleeved on the shank of the bolt member, and has an article confronting side and a nut confronting side opposite to the article confronting side of the washer. The article confronting side of the washer is formed with a plurality of anti-skid projections that are angularly spaced apart and that extend in radial outward directions relative to the shank of the bolt member. The nut engages threadedly the externally threaded section of the shank, and has opposing first and second surfaces respectively disposed remote from and proximate to the nut confronting side of the washer such that the second surface of the nut urges the nut confronting side of the washer toward the head of the bolt member.